package PTA2.ti2201;

import java.util.Scanner;

/**
 * @author Lenovo
 */
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int number=scanner.nextInt();
        int hundred=number/100;
        int ten=(number%100)/10;
        int unit=number%10;
        int sum=hundred+ten+unit;
        System.out.println(sum);
    }
}
